Pressure sensitive record sheets employing 3 - (phenyl) - 3-(indol - 3 - yl)-phthalides



Nov. 17, 1970 CHAD-HAN LIN 3,540,91

PRESSURE SENSITIVE RECORD SHEETS EMPLOYING S-(PHENYLI-S-INDOL-S-YLI-PHTI-IALIDES Original Filed Jan. 50, 1967 BASE-SHEET OFRECORD MATERIAL COATED ON THE REAR WITH MINUTE PRESSURE-RUPTURABLECAPSULES CONTAINING LIQUID SOLUTION 0F CHROMOGENIC MATERIAL DEVELOPABLEON CONTACT WITH AN ELECTRON- ACCEPTING MATERIAL OF THE LEWIS- ACID TYPETO COLORED FORM.

RECEIVING SURFACE OF UNDERSHEET COATED WITH AN ELECTRON-ACCEPTINGMATERIAL OF THE LEWIS-ACID TYPE INVENTOR CHAD-HAN LIN United StatesPatent Office 3,540,911 Patented Nov. 17, 1970 3,540,911 PRESSURESENSITIVE RECORD SHEETS EM- PLOYING 3 (PHENYL) 3-(INDOL 3 YL)-PHTHALIDES Chao-Han Lin, Dayton, Ohio, assignor to The National CashRegister Company, Dayton, Ohio, a corporation of Maryland Originalapplication Jan. 30, 1967, Ser. No. 612,459, now Patent No. 3,491,116,dated Jan. 20, 1970. Divided and this application Jan. 24, 1969, Ser.No. 821,537

Int. Cl. B41m /22 US. Cl. 117-36.2 38 Claims ABSTRACT OF THE DISCLOSUREA pressure sensitive record unit and method of marking employingchromogenic material normally colorless form, having a structuralformula:

wherein R and R comprise alkyl radicals having from one to five carbonatoms, aryl radicals, and hydrogen; and R and R comprise alkyl radicalshaving from one to five carbon atoms and hydrogen; said material assuming a colored form upon contact with a Lewis acid molecule. Examplesinclude 3 (p-dimethylaminophenyl) -3 1,2-dimethylindol- 3-y1 phthalide;

3- (p-dimethylaminophenyl) -3- (Z-methylindol- 3-yl) phthalide;

3- p-di-n-butylaminophenyl -3- Z-dimethylindol- 3 -yl) phthalide;

3 (p-di-n-butylaminophenyl -3- Z-methylindol- 3-yl) phthalide;

3- (p dimethylaminophenyl -3 2-phenylindol-3- yl) phthalide;

3- (p-dimethylaminophenyl -3 l-methyl-Z-phenylindol- 3 -yl) phthalide;

3 (p-diethylaminophenyl -3 Z-phenylindol- 3 -yl) phthalide.

This is a division of application Ser. No. 612,459, filed Jan. 30, 1967,now US. Pat. No. 3,491,116.

This invention pertains to novel chromogenic compounds for use inpressure sensitive record material and to an improved mark-formingmanifold system incorporating these novel chromogenic compounds. Morespecifically, this invention pertains to 3-dialkylaminophenyl-3-indolylphthalides which have the form of substantially colorless, i.e. white,or slightly colored solids, or approach being colorless when in liquidsolution, but which may be converted to dark-colored forms upon reactivecontact with acidic material. As used in mark-forming systems, markingin desired areas on support webs or sheets may be accomplished byeffecting localized reactive contact between the chromogenic materialand the acidic material on or in such a web or sheet, such materialbeing brought thereto by transfer, or originally there in situ, thedesired reactive contact forming dark-colored materials in the intendedimage areas.

Pressure-sensitive, mark-forming systems of the prior art include thatdisclosed in application for Letters Patent No. 392,404, filed Aug. 27,1964, by Robert E. Miller and Paul S. Phillips, Jr., now abandoned. Thelatter application provides a marking system of disposing on and/ orwithin sheet support material the unreacted markforming components (atleast one of which is a polymeric material) and a liquid solvent inwhich each of the markforming components is soluble, said liquid solventbeing present in such form that it is maintained isolated by apressure-rupturable barrier from at least one of the markformingcomponents until the application of pressure causes a breach or ruptureof the barrier in the area delineated by the pressure pattern. Themark-forming components thereby are brought into reactive contact,producing a distinctive mark.

It is an object of this invention to provide new and improved substanceshaving chromogenic properties which may be incorporated in a web orcoated onto the surface of a web to provide a novel manifolding unit,and which are useful in carrying out improved methods of markinginvolving reactive contact with a color-activating material to developdark-colored materials in areas where marking is desired.

It is another object of this invention to provide modified compounds,based upon the 3-(p-dialkylaminophenyl)-3-indolyl phthalides, which aresubstantially colorless, or slightly colored offering a new and improvedvariety of chromogenic characteristics, and developing noveldark-colored substance upon contact with color-activating materials.

It is a further object of this invention to provide a new and improvedmark-forming system which has the form of disposing within a web or uponthe surface of a web or sheet support material unreacted chromogenicmaterial which is capable of being reactively contacted with an acidicmaterial to produce a dark-colored substance, thus providing markshaving desirable color intensity and hue.

In accordance with this invention, there is provided a novel,substantially colorless or slightly colored chromogenic compound havingthe structural formula:

wherein R and R comprise alkyl radicals having from 1 to 5 carbon atoms,aryl radicals, and hydrogen; and R and R comprise alkyl radicals havingfrom 1 to 5 carbon atoms and hydrogen. Examples of these novel compoundsare 3-(p-dimethylaminophenyl)-3-(1,2-dimethylindol-3-yl) phthalidehaving the structural formula:

CHs

3-(p-dimethylaminophenyl) 3 (2 methylindol-3-yl) phthalide having thestructural formula:

3-(p-di-n-butylaminophenyl) 3 (2-methylindol-3-yl) phthalide having thestructural formula:

CH- 1 a 3 (p-dimethylaminophenyl) 3 (2-phenylindol-3-yl) phthalidehaving the structural formula:

2O 2 a t l t n H 5 7 O 3 (p-dimethylaminophenyl) 3(l-methyl-Z-phenylindol-3-yl)phthalide having the structural formula:

1 N 4 o H CH3 5 7 0 3 (p-diethylaminophenyl) 3 (2-phenylindol-3-yl)phthalide having the structural formula:

on-15) 2-N-Q In accordance with another feature of this invention, a newcomposition of matter comprises the dark-colored substance having aresonant form developed by contact of a color-activating material withone of the abovementioned chromogenic compounds. The color-developing oractivating material is an acidic substance for converting thechromogenic compound to the resonant form.

The method of marking of this invention, i.e., by developing adark-colored material from substantially colorless or slightly coloredchromogenic compounds comprises providing a chromogenic compoundselected from among the above-mentioned compounds and bringing suchchromogenic compound into reactive contact in areas where marking isdesired with an acidic color-activating substance to produce adark-colored resonant form of the chromogenic compound by the actionthereon in said areas of the said acidic substance.

The acidic materials in this invention can be any compound within thedefinition of a Lewis acid, i.e., an electron acceptor. Preferably,acidic organic polymers such as phenolic polymers are employed as theacidic material. The novel chromogenic materials exhibit the advantageof improved color stability when reacted with such phenolic polymers.The solution formation of the solid particles of polymeric material inthe same solvent with the substantially colorless chromogenic compoundsallows penetration of the color into the support sheet, if porous, e.g.,paper, so that the colored form of the chromogenic material sinks intothe body of the sheet and is not merely on the surface of the sheet.This feature protects against erasure of recorded data by attrition ofthe surface of the record sheet.

Reference is directed to the drawings. FIG. 1 is a diagrammaticrepresentation of a two-sheet unit manifold, a perspective in which thebottom surface of the overlying is supplied on the surface or near itWith a multiplicity of minute pressure-rupturable microcapsules, eachcontaining a droplet. Each droplet contains a solution of the basicchromogenic component. An acidic component, such as an acid clay or aphenolic polymeric material lies within the lower web or sheet or uponthe upper surface of the lower Web or sheet. A colored mark is made bythe use of a stylus, a type character, or other pressure-writing meansapplied to the two-sheet unit manifold.

The encapsulated droplets are released on the rupture of the capsules inwriting operations, as shown in FIG. 1a. The liquid of the releaseddroplets is transferred in the pattern of the data configuration to thetop of the underlying sheet. The top of the underlying sheet is coatedor impregnated with a material reactant with the chromogenic material,e.g., a phenolic polymer material having an acid-reacting OH group. Thedrawing show capsules on the over sheet containing a liquid solution ofchr0- mogenic material. However, the capsules can contain the polymericphenolic material in liquid solution and the top surface of theunder-sheet may be supplied with the chromogenic material in particulateform. The improvement in the system is the chromogenic compound which isthe novel substance of the instant invention.

Referring again to FIG. 1 comprising an upper web or sheet having thechromogenic material dispersed within or upon in a contiguousjuxtaposition, it is possble to incorporate the chromogenic material ina solid, crystallne-state in a binder material so that the chromogen icmaterial may be transferred from the upper web or sheet upon theapplication of pressure from a stylus to deposit some of the chromogenicmaterial on a surface carrying a color activating polymeric material.Preferably, the chromogenic substance is dissolved in a solvent andminute droplets of the solution of the chromogenic material areencapsulated in minute, rupturable capsules. Obviously, many otherarrangements, configurations and relationships of the solvent and themark-forming materials, with respect to their encapsulation and locationon the supporting sheet or webs can be envisioned. Such arrangements arethoroughly described in the aforementioned application 'S.N. 392,404 toMiller et al., and need not be repeated herein.

It is noted that the polymeric mark-forming components should have acommon solubility with the chromogenic material in at least one liquidsolvent when the acidreacting material is a phenolic or other organicacidic polymer. It is also noted that in a single system severalchromogenic materials may be used with the same or different polymericmaterials. Several polymeric materials can be reactively contacted witha single chromogenic compound or with a mixture of chromogeniccompounds.

As mentioned above, the solvent is maintained in physical isolation inminute droplets until such time as it is released by application ofpressure. This may be accomplished by several known techniques, butpreferably isolation is maintained by individual encapsulation of thesolvent droplets in a microcapsule according to the proceduresdescribed, for example, in U.S. Pat. No. 2,712,507, issued to Barrett K.Green on July 5, 1955; 2,730,457 issued to Barrett K. Green and LowellSchleicher on Jan. 10, 1956; 2,800,457, issued to Barrett K. Green andLowell Schleicher on July 23, 1957; and 2,800,458, issued to Barrett K.Green on July 23, 1957, reissued as Re. Pat. No. 24,899 on Nov. 29,1960. The microscopic capsules, when disposed within or upon asupporting web as a multiplicity in contiguous juxtaposition, arerupturable by pressure, such as normal marking pressures utilized, forexample, in writing or typing operations.

The material or mateirals chosen as the wall material of themicrocapsule, in addition to being pressure rupturable, must be inert orunreactive in respect to the contents of the capsule and the othermark-forming components so that the wall material remains intact undernormal storage conditions until each time as it is released by theapplication of marking pressure. Examples of such wall materials aregelatin, gum arabic and many others thoroughly described in theaforementioned patents.

For use in record material, the capsule size should not exceed 50microns in diameter. Preferably, the capsules should be smaller thanmicrons in diameter- The acidic organic polymeric material useful inthis invention include phenolic polymers, phenol acetylene polymers,maleic acid-rosin resins, partially or wholly hydrolyzed styrene-maleicanhydride copolymers and ethylene-maleic anhydride copolymers, carboxypolymethylene and wholly or partially hydrolyzed vinyl methyl ethermaleic anhydride copolymer and mixtures thereof.

Phenolic polymers found useful include alkyl-phenolacetylene resins,which are soluble in common organic solvents and possess permanentfusibility in the absence of being treated by cross-linking materials. Aspecific group of useful phenolic polymers are members of the typecommonly referred to as novolacs, (as sold by Union Carbide Corp., NewYork, N.Y.) which are characterized by solubility in common organicsolvents and which are, in the absence of cross-linking agents,permanently fusible. Generally, the phenolic polymer material founduseful in practicing this invention is characterized by the presence offree hydroxyl groups and the absence of groups such as methylol, whichtend to promote infusibility or cross-linking of the polymer, and bytheir solubility in organic solvents and relative insolubility inaqueous media. Again, obviously, mixtures of these organic polymers andother acidic materials can be employed.

Resoles, if they are still soluble, may be used, though subject tochange in properties upon aging.

A laboratory method useful in the selection of suitable phenolic resinsis the determination of the infra-red absorption pattern. It has beenfound that phenolic resins showing an absorption in the 32003500 cm.region (which is indicative of the free hydroxyl groups) and not havingan absorption in the 16001700 cm. region are suitable. The latterabsorption region is indicative of the desensitization of the hydroxylgroups and, consequently, makes such groups unavailable for reactionwith the chromogenic materials.

The preparation of organic polymeric materials for practicing thisinvention is described in Industrial and Engineering Chemistry, volume43, pages 134 to 141, January 1951, and a particular polymer thereof isdescribed in Example I of US. Pat. No. 2,052,093, issued to HerbertHonel on Aug. 25, 1936, and the preparation of the phenol-acetylenepolymers is described in Industrial and Engineering Chemistry, volume41, pages 73 to 77, January 1949.

The preparation of the maleic anhydride copolymers is described in theliterature, such as, for example, one of the maleic anhydride vinylcopolymers, as disclosed in the publication, Vinyl and Related Polymers,by Calvin E. Schildknecht, Second printing, published April 1959, byJohn Wiley & Sons, Incorporated. See pages 65 to 68 (styrene-maleicanhydride copolymer), 628 to 630 (vinyl methyl ether-maleic anhydridecopolymer), and 530 to 531 (ethylene-maleic anhydride copolymer).

When the acidic material is one of the aforementioned organic polymers,the liquid solvent chosen must be capable of dissolving the mark-formingcomponents. The solvent may be volatile or non-volatile, and a single ormultiple component solvent may be used which is wholly or partiallyvolatile. Examples of volatile solvents useful in the afore-describedbasic chromogen-acidic polymer are toluene, petroleum distillate,perchloroethylene, and xylene. Examples of non-volatile solvents arehigh-boiling point petroleum fractions and chlorinated biphenyls.

Generally, the solvent chosen should be capable of dissolving at least0.3%, on a weight basis, of the chromogenic material, and about a 3-5 ona weight basis, of the polymeric material to form an eflicient reaction.However, in the preferred system, the solvent should be capable ofdissolving an excess of the polymeric material, so as to provide everyopportunity for utilization of the chromogenic material and, thus, toassure the maximum coloration at a reaction site.

A further criterion of the solvent is that it must not interfere withthe mark-forming reaction. In some instances, the presence of thesolvent may interfere with the mark-forming reaction or diminish theintensity of the mark, in which case the solvent chosen should besufficiently vaporizable to assure its removal from the reaction siteafter having, through solution, brought the mark-forming components intointimate admixture, so that the mark-forming contact proceeds.

Since the mark-forming reaction requires an intimate mixture of thecomponents to be brought about through solution of said components, oneor more of the markforming components may be dissolved in the isolatedsolvent droplets, the only requirement being that at least one of thecomponents essential to the mark-forming reaction be maintained isolateduntil reactively contacted with the other.

In the usual case, the mark-forming components are so chosen as toproduce a mark upon application of pressure at room temperature todegrees centigrade). However, the present invention includes a system inwhich the solvent component is not liquid at temperatures around roomtemperature but is liquid and in condition for forming solutions only atelevated temperatures.

The support member on which the components of the system are disposedmay comprise a single or dual sheet assembly. In the case where allcomponents are disposed on a single sheet, the record material isreferred to as a self-contained system. Where there must be a migrationof the solvent, with or without mark-forming component, from one sheetto another, the record material is referred to as a transfer system.Such a system may also be referred to as a two-fold system, in that atleast two sheets are required and each sheet includes a component, orcomponents, essential to the mark-forming reaction.) Where a copiousamount of the colored reaction product in liquid form is produced on asurface of one sheet, it may produce a mark by transfer to a secondsheet as a colored mark.

In the preferred case, where microcapsules are employed, they may bepresent in the support material either disposed therethroughout or as acoating thereon, or both. The capsules may be applied to the sheetmaterial while still dispersed in the liquid vehicle in which they weremanufactured, or, if desired, separated and the separated capsulesthereafter dispersed in a solution of the polymeric component (forinstance, grams of water and 53 grams of a 1% aqueous solution ofpolyvinyl methyl ether maleic anhydride) to form a coating compositionin which, because of the inertness of the solution and the capsules,both retain their identity and physical integrity. When this compositionis disposed as a film on the support material and dried, the capsulesare held therein subject to rupture to release the liquid contained.This latter technique, relying on the inertness of the microcapsule andthe dispersing medium of the film-forming mark-forming component, allowsfor a method of preparing a sensitive record coating with the capsulesinterpersed directly in a dry film of the polymeric material as it islaid down from the solution. A further alternative is to disperse in aliquid medium one or more mark-forming components, insoluble therein,and disperse in said medium the insoluble microcapsules, with the resultthat all components of the markforming system may be disposed on orwithin the support sheet in the one operation. Obviously, the severalcomponents may be applied individually.

The respective amounts of the several components will vary, dependingprimarily upon the nature of the materials and the architecture of therecord material unit. Suitable lower amounts include, in the case of thechromogenic material, about .005 to .075 pound per ream (a ream in thisapplication meaning five hundred (500) sheets of 25" x 38" paper,totalling 3,300 square feet); in the case of the solvent, about 1 to 3pounds per ream; and in the case of the polymer, about V2 pound perream. In all instances, the upper limit is primarily a matter ofeconomic consideration.

In the instance where the mark-forming components are interspersedthroughout a single support sheet material (so-called self-containedunit), the following technique or procedure has been found useful:

The slurry of capsules may be applied to a wet web of paper as it existson the screen of a Fourdrinier paper machine, so as to sink the paperweb a distance depending on the freeness of the pulp and the Watercontent of the web at the point of application.

The capsules may be placed directly in the paper or in a support sheet.Not only capsule structures, but films which hold a multitude ofdroplets for local release in an area subject to pressure may beutilized. (See US. Pat. No. 2,299,694 which issued Oct. 20, 1942, to B.K. Green.)

With respect to the acidic organic polymeric component, a solutionthereof in an evaporable solvent is introduced into twice as much waterand agitated while the evaporable solvent is blown off by an air blast.This leaves an aqueous colloidal dispersion slurry of the polymericmaterial, which may be applied to the paper so as to leave a surfaceresidue, or the slurry may be applied to paper at the size-press stationof a paper making machine by roller. In another method of making apolymer-sensitized sheet, the Water-insoluble polymer is ground to thedesired particle size in a ball mill with water, preferably with adispersing agent, such as a small quantity of sodium silicate. If abinder material of hydrophilic properties is ground with the phenolicmaterial, the binder itself may act as a dispersant. If desired, anamount of binder material of up to 40%, by weight, of the employedamount of the polymeric material may be added to the ball-milled slurryof materials, such binder materials being of the paper coating binderclass, in cluding gum arabic, cascin, hydroxyethylcellulose, and latex(such as styrene-butadiene copolymer). If desired, oil adsorbents in theform of fullers earths may be added to the polymeric material particlesto assist in retaining, in situ, the liquid droplets to be transferredto it in datarepresenting configuration, for the purpose of preventingbleeding of the print.

Another way of applying the chromogenic or polymeric materialindividually to a single sheet of paper is by immersing a sheet of paperin a 1% to solution of the material in an evaporable solvent. Obviously,this must be done alone for each reactant, because if the other reactantmaterial were present, it would result in a premature coloration overthe sheet area. A dried sheet with one component then may be coated witha solution of the other component, the solvent of which is a non-solventto the already supplied component.

The polymeric material may be dissolved in ink composition vehicles toform a printing ink of colorless character and, thus, may be used tospot-print a proposed record sheet unit sensitized for recording in areactionproduced color in those areas by application of a solution ofthe chromogenic material.

In the case of phenolic polymer, a printing ink may be made of up to 75%weight, of the phenolic polymeric material in a petroleum solvent to aviscosity suitable for printing purposes. The relative amounts ofcomponents to be used are the most convenient and economical amountsconsistent with proper visibility of the recorded data. The resolutionof the recorded data is, among other things, dependent on particle size,distribution and amount of particles, liquid solvent migration, chemicalreaction efiiciency, and other factors, all of which are things that maybe worked out empirically by one familiar with the art, and which do notdetermine the principle of the invention, which, in part, involves meansfor enabling the bringing into solution, by marking pressure, of twonormally solid components in a common liquid solvent component heldisolated as liquid droplets, preferably in marking-pressure-rupturablecapsules having film walls, or else held isolated in a continuousmarking-pressurerupturable film as a discontinuous phase.

In the base-acid color system of this invention the acidic mark-formingcomponent(s) reacts with the basic chromogenic material(s) to effectdistinctive color formation or color change. In a multi-sheet system inwhich an acidic organic polymer is employed, it is desirable to includeother materials to supplement the reactants. For example, kaolin can beadded to improve the transfer of the liquid and/or the dissolvedmaterials between the sheets. In addition, other materials such asbentonite, attapulgite, talc, feldspar, halloysite, magnesiumtrisilicate, silica gel, pyrophyllite, zinc sulfate, zinc sulfide,calcium sulfate, calcium citrate, calcium phosphate, calcium fluoride,barium sulfate and tannic acid can be included.

Various methods known to the prior art and disclosed in theaforementioned application S.N. 392,404 to Miller et al. and US. patentapplication S.N. 420,193 to Phillips et al. can be employed in coatingcompositions of the mark-forming materials into their supporting sheets.An example of the compositions which can be coated onto the surface ofan underlying sheet of a two-sheet system to react with the capsulecoating on the underside of an overlying sheet is as follows.

Coating composition: Percent by wt.

Phenolic polymer mixture 17 Paper coating kaolin (white) 57 Calciumcarbonate l2 Styrene butadiene latex 4 Ethylated starch 8 Gum arabic 2EXAMPLE I 40 minutes and at 5560 C. for 30 minutes. Upon cooling to roomtemperature, the benzene solvent was removed by extraction withpetroleum ether, and the residue was decomposed with 34 milliliters of17% sulfuric acid. After partial neutralization with about millilitersof concentrated ammonium hydroxide, the sulfuric acid solution wasdiluted with water to a volume of 900 milliliters and stirred for anadditional 30 minutes. The precipitate formed was removed by filtration,and exhibited a weight of 13.5 grams and a melting point of 195200 C.The crude intermediate was recrystallized from dilute sulfuric acid,thereupon exhibiting a melting point of 200-203 C.

The preparation of 3-(p-dimethylaminophenyl)-3-(1,2- dimethylindol-3-yl)phthalide was effected by the following process:

The keto-acid, prepared in the process set forth above was used in thispreparation. 5.4 grams of 4-dimethylaminobenzophenone-Z-carboxylic acidand 3.2 grams of 1,2-di-methylindole were mixed with twenty millilitersof acetic anhydride. After being heated for fifteen minutes to near theboiling point on a hot plate, the reaction mixture was poured into onehundred milliliters of water and heated for an additional ten minutes.Upon cooling, the mixture was treated with ammonium hydroxide until itwas strongly alkaline, then stirred for ten minutes. The solid whichexhibited a weight of 7.8 grams, was removed by filtration purified byrecrystallization from a benzene solution.

The purified product exhibited a melting point of 226- 228 C. A solutionof the product in benzene turned a vivid blue when applied to a papersheet coated with a phenolic polymer, but imparted a blue-purple colorto paper coated with attapulgite clay.

EXAMPLE II The preparation of 3-(p-dimethylarninophenyl)-3-(2-methylindol-B-yl) phthalide was effected in the following process:

5.4 grams of the 4'-dimethylaminobenzophenone-2- carboxylic acidprepared in the foregoing procedure, were mixed with 2.9 grams ofZ-methylindole and 20 milliliters of acetic anhydride and heated to theboiling point of the mixture on a hot plate for fifteen minutes. Aproduct was isolated according to the procedure described in Example I.The product exhibited a weight of 8.6 grams and was purified byrecrystallization from benzene. The purified product exhibited a meltingpoint of 211-212 C. The color of the product when dissolved in benzeneand reacted with paper coated with phenolic polymer was blue.

EXAMPLE III The compound3-(p-di-n-butylaminophenyl)-3-(1,2-dimethylindol-3-yl) phthalide wasprepared in the following procedure:

24.6 grams of di-n-butylaniline, 14.8 grams of phthalic anhydride, and20 milliliters of benzene were stirred in a 100 milliliter flaskimmersed in a cold water bath. 26.7 grams of aluminum chloride wasslowly added, the addition requiring ten minutes. The Water bathtemperature was raised to 50 C. in thirty minutes, and maintained at 50C. to 54 C. for one hour. The Water bath was removed and the flaskcooled to room temperature. The reaction mixture was then decomposedwith 150 milliliters of 20% sulfuric acid, resulting in the formation ofan oil floating as a supernatant layer. 400 milliliters of water wereadded, causing the oil to change to a semisolid phase. The aqueoussolution was decanted and the semi-solid material was Washed twice with400 milliliter quantities of water.

The semi-solid material was then stirred with 1200 milliliters of waterfor one hour. The semi-solid material disintegrated into a light-greencolored precipitate. The water was decanted and fresh water added. Afterthree hours a powdered solid product was precipitated exhibiting aWeight of 18.4 grams and a melting point range of 164168 C. 5 grams ofthe solid intermediate product, 4-di-n-butylaminobenzophenone 2carboxylic acid was dissolved in 50 milliliters of toluene, treated withcharcoal and filtered. A yellow filtrate was treated with an equalvolume of petroleum ether yielding a yellow precipitate exhibiting aweight of 4.7 grams and a melting point range of 168-l70 C.

1.06 grams of the 4'-di-n-butylaminobenzophenone-2- carboxylic acidproduct of the foregoing procedure, 0.44 gram of 1,2-dimethylindole and10 milliliters of acetic anhydride were heated in a thirty milliliterbeaker to a temperature slightly below the boiling point of the mixturefor 15 minutes. The reaction mixture was poured into milliliters ofwater, made alkaline by the addition of ammonium hydroxide, and stirredfor two hours. A product precipitated which exhibited a weight of 1.3grams. The product, 3-(p-di-n-butylaminophenyl)-3-(1,2-dimethylindol-3-yl) phthalide was dissolved in 30 milliliters ofbenzene, treated with activated charcoal, and filtered. The filtrate wasconcentrated to 5 milliliters and further purified to yield a purifiedproduct exhibiting a weight of 1.05 grams and a melting point range of140- 141.5 C. A benzene solution of the product appeared purple whencontacted with attapulgite clay coated on paper and blue when contactedwith phenolic polymer coated on paper.

EXAMPLE IV Preparation of3-(p-di-n-butylaminophenyl)-3-(2-methylindol-3-yl) phthalide.

3.5 grams of the intermediate4'-di-n-butylaminobenzophenone-Z-carboxylic acid, prepared as describedin Example III, 1.3 grams of 2-methylindole, and 25 milliliters ofacetic anhydride were heated to boiling for 15 minutes, poured into 125milliliters of water, made alkaline with ammonium hydroxide and stirredfor minutes. A precipitate was separated and purified, repeatedly, froma mixture of benzene and petroleum ether. A product thus obtained meltedat l57.5159.5 C. A benzene solution of the product turned a purple colorwhen contacted with attapulgite clay coated on paper but blue whencontacted with a phenolic resin coated on paper.

EXAMPLE V The preparation of 3-(p-dimethylaminophenyl)-3-(2-phenylindol-3-yl) phthalide was effected by the following process:

2.7 grams of 4-dirnethylaminobenzophenone-Z-carboxylic acid prepared inthe procedure set forth in Example I was mixed with 2.1 grams of2-phenylindole and forty milliliters of acetic anhydride. A crudeproduct, weighing 4.4 grams, was isolated according to the proceduredescribed in Example I. The product was recrystallized from the benzenesolution. The purified product exhibited a melting point of 252253 C.The benzene solution of the product imparted a green color to papercoated with a phenolic polymer.

EXAMPLE VI The preparation of 3-(p-dimethylaminophenyl)-3-(1-methyl-2-phenylindol-3-yl) phthalide was effected by the followingprocedure.

0.8 gram of 4'-dimethylaminobenzophenone-2-carboxylic acid prepared inthe procedure set forth in Example I, 0.62 gram ofl-methyl-Z-phenylindole and 5 milliilters of acetic anhydride werereacted as set forth in Example III. Following the isolation procedureof Example III, a crude product weighing 1.0 gram was obtained uponrecrystallization from 95% ethanol, a pure product exhibiting a meltingpoint range of 146 C. to 148 C. was obtained. A solution in benzene ofthe 3-(p-dimethylaminophenyl)- 3-(l-methyl-2-phenylindol-3-yl) phthalideproduct appeared a blue color when reacted with attapulgite clay coatedon paper and appeared green when contacted with a phenolic polymercoated onto paper.

1 1 EXAMPLE VII The compound 3-(p-diethylaminophenyl)-3-(2-phenylindol-3-yl)phthalide was prepared inthe following procedure:

An intermediate keto-acid 4'-diethylarninobenzophenone-Z-carboxylic acidwas first prepared by stirring 18.0 grams of diethylaniline, 14.8 gramsof phthalic anhydride, and 20 milliliters of benzene in a 100 milliliterflask immersed in a cold water bath. 26.7 grams of aluminum chloride wasslowly added to the reaction mixture, the addition requiring 12 minutes.The Water bath temperature was raised to 52 C. over a period of thirtyminutes and maintained at 52-55 C. for 70* minutes. Twenty millilitersof water were added, followed by the addition of 200 milliliters of 20%sulfuric acid to the reaction mixture. Upon heating a turbid solutionwas observed. The solution was diluted with water to 800 milliliters andneutralized with ammonium hydroxide to a pH of 1.8. A semi-solid phaseappeared and was separated and stirred into an 800 milliliter quantityof water for 120 minutes. A solid precipitate was formed which exhibiteda weight of 15.7 grams and a melting point range of 173- 177 C. Thecrude material was purified by dissolving said material in 4 normalsulfuric acid, filtering the solution to remove insoluable material, andreprecipitating the product with ammonium hydroxide. The melting pointof the 4'-diethylaminobenzophenone-2-carboxylic acid intermediate wasthereby raised to ISO-181 C.

The intermediate keto-acid prepared in the foregoing procedure was usedin the preparation of the compound3-p-diethylaminophenyl-3-(2-phenylindol 3 yl) phthalide by heating 0.74gram of 4'-diethylaminobenzophenone-2-carboxylic acid, 0.48 gram of2-phenylindole and milliliters of acetic anhydride in a beaker over ahotplate for 15 minutes. The reaction mixture was poured into 100milliliters of water, made alkaline with ammonium hydroxide and stirredfor 60 minutes. A crude product exhibiting a Weight of 1.1 grams wasprecipitated. The crude product was dissolved in 50 milliliters ofbenzene, treated with charcoal and filtered. The filtrate upon standingyielded a 3-(p-diethylaminophenyl)-3-(2-phenylindol- 3-yl) phthalideproduct exhibiting a melting point of 246 247 C. A benzene solution ofthe product appeared a blue-green color when contacted with attapulgiteclay coated on paper and a green color when contacted with a phenolicpolymer coated on paper.

What is claimed is:

1. A pressure sensitive record unit comprising:

(a) support web or sheet material,

(b) mark-forming components and a releasable liquid solvent for saidmark-forming components arranged in contiguous juxtaposition andsupported by said sheet material,

(c) said mark-forming components comprising at least one chromogenicmaterial of the structure:

wherein R and R consist of alkyl having from one to four carbon atomsphenyl and hydrogen; and where R and R consist of alkyl having from oneto four carbon atoms and hydrogen; and an electronaccepting material ofthe Lewis acid type reactive with said chromogenic material to produce amark; which components upon pressure-release of the liquid solvent arebrought into reactive contact in the released solvent.

2. The record unit of claim 1 wherein at least one of the mark-formingcomponents is maintained in isolation from the other mark-formingcomponents prior to the release of the solvent.

3. The record unit of claim 1 wherein the liquid solvent is present asthe nucleus of a microcapsule.

4. The record unit of claim 1 wherein the chromogenic material isdissolved in the isolated liquid solvent prior to pressure release.

5. The record unit of claim 1 wherein the mark-forming components andthe isolated liquid solvent are present in a single support sheet.

6. The record unit of claim 1 wherein at least one member selected fromthe group consisting of the markforming components and the liquidsolvent is present in a support sheet other than the support sheethaving the remaining members of the group.

7. The record unit of claim 1 where the electron-accepting material ofthe Lewis acid type comprises a clay.

8. The record unit of claim 1 where the electron-accepting material ofthe Lewis acid type comprises at least one organic polymer.

9. The record unit of claim 8 where the organic polymer is a phenolicpolymer.

10. The record unit of claim 1 wherein the chromogenic materialcomprises the compound 3-(p-dimethylaminophenyl) -3- l,2-dimethylindol-3-yl) phthalide.

11. The record unit of claim 1 wherein the chromogenic materialcomprises the compound 3-(p-dimethylaminophenyl -3- 2-methylindol-3-yl)phthalide.

12. The record unit of claim 1 wherein the chromogenic materialcomprises the compound 3-(p-di-n-butylaminophenyl -3-(1,2-dimethylindol-3-yl) phthalide.

13. The record unit of claim 1 wherein the chromogenic materialcomprises the compound 3-(p-di-n-butylaminophenyl -3-(Z-methylindol-B-yl) phthalide.

14. The record unit of claim 1 wherein the chromogenic materialcomprises the compound B-(p-dimethylaminophenyl) -3- 2-phenylindol-3-yl)phthalide.

15. The record unit of claim 1 wherein the chromogenic materialcomprises the compound 3-(p-dimethylaminophenyl -3-(1-methyl-2-phenylindol-3-yl) phthalide.

16. The record unit of claim 1 wherein the chromogenic materialcomprises the compound 3-(p-diethylaminophenyl)-3-(2-phenylindol-3-yl)phthalide.

17. A mark-forming unit, comprising: a first web or sheet having on onesurface a transfer coating which contains as a finely dispersed phase aplurality of minute, pressure-rupturable capsules containing as an innerphase a solvent vehicle; a second Web or sheet having an adherentcoating upon its surface or dispersed within said web or sheet, saidfirst and second webs or sheets being maintained disposed together inface-to-face relationship with said respective transfer and adherentcoatings in contiguity with each other; a first coating constituent inthe form of a substantially colorless or slightly colored chromogenicmaterial which includes as a major functional arrangement the molecularstructure where R and R consist of alkyl having from one to four carbonatoms, phenyl and hydrogen; and where R and R consist of alkyl havingfrom one to four carbon atoms and hydrogen; and a second constituent inthe form of an electron-accepting material of the Lewis acid type; oneof said constituents being dissolved in said solvent liquid vehiclepresent as the inner phase of the plurality of minutepressure-rupturable capsules in the transfer coating on or within saidfirst web or sheet, and the other of said coating constituents beingbonded to said second web in said adherent coating thereon but beingaccessible to other materials coming into contact with portions of theadherent coating, whereby, upon local impact and rupture of saidcapsules, releasing said liquid vehicle containing one coatingconstituent from at least some of the capsules onto said contiguousadherent coating, reactive contact is eifected between said twoconstituents to produce a dark-colored material by the action of saidelectron-accepting material of the Lewis acid type upon said chromogenicmaterial to effect color change in said chromogenic compound to saiddark-colored material.

18. The mark-forming unit of claim 17 in which the electron-acceptingmaterial of the Lewis acid type comprises a clay.

19. The mark-forming unit of claim 17 in which the electron-acceptingmaterial of the Lewis acid type comprises an organic polymer.

20. The mark-forming unit of claim 19 in which the organic polymer is aphenolic polymer.

21. The mark-forming unit of claim 17 in which at least one chromogeniccompound is 3-(p-dimethylaminophenyl)-3-(1,2-dimethylindol-3-yl)phthalide.

22. The mark-forming unit of claim 17 in which at least one chromogeniccompound is 3-(p-dimethylaminophenyl)-3-(2-methylindol-3-yl) phthalide.

23. The mark-forming unit of claim 17 in which at least one chromogeniccompound is 3-(p-di-n-butylaminophenyl) -3-( 1,2-dimethylindol-3-yl)phthalide.

24. The mark-forming unit of claim 17 in which at least one chromogeniccompound is 3-(p-di-n-butylaminophenyl)-3-(2-methylindol-3-yl)phthalide.

25. The mark-forming manifold of claim 17 in which at lea-st onechromogenic compound is 3-(p-dimethylaminophenyl -3 2-phenylindol-3 -yl)phthalide.

26. The mark-forming manifold of claim 17 in which at least onechromogenic compound is 3-(p-dimethylaminophenyl -3-1-methyl-2-phenylindol-3-yl) phthalide.

27. The mark-forming manifold of claim 17 in which at least onechromogenic compound is 3-(diethylaminophenyl) -3-(2-phenylindol-3-yl)phthalide.

28. The method of marking on a substrate by developing dark-coloredmaterials from chromogenic compounds comprising: providing as at leastone constituent a colorless or slightly colored chromogenic compoundhaving the structural formula:

Where R and R consist of alkyl having from one to four carbon atoms,phenyl and hydrogen; and where R and R consist of alkyl having from oneto four carbon atoms and hydrogen, and bringing said chromogeniccompound into contact, in areas on said substrate sheet where marking isdesired, with an electron-accepting material of the Lewis acid type toproduce marks in said areas of a dark-colored material formed by theaction of said electron-accepting material on said chromo-geniccompound.

29. The method of claim 28 in which the electronaccepting material ofthe Lewis acid type is a clay.

30. The method of claim 28 in which the electronaccepting material ofthe Lewis acid type is an organic polymer.

31. The method of claim 30 in which the electronaccepting organicpolymer is a phenolic polymer.

32. The method of claim 28 in which at least one chromogenic compound is3-(p-dimethylarninophenyl)-3- (1,2-dimethylindol-3-yl) phthalide.

33. The method of claim 28 in which at least one chromogenic compound is3-(p-dimethylaminophenyl)-3- (2-methylindol-3-yl) phthalide.

34. The method of claim 28 in which at least one chromogenic compound is3-(p-di-n-butylaminophenyl)-3 (1,2-dimethylindol-3-yl) phthalide.

35. The method of claim 28 in which at least one chromogenic compound is3-(p-di-n-butylaminophenyl)- 3-(2-methylindol-3-yl) phthalide.

36. The method of claim 28 in which at least one chromogenic compound is3-(p-dimethylaminophenyl)-3-(2- phenylindol-3-yl) phthalide.

37. The method of claim 28 in which at least one chromogenie compound is3-(p-dirnethylaminophenyl)-3-(lmethyl-2-phenylindol-3-yl) phthalide.

38. The method of claim 28 in which at least one chromogenic compound is3-(p-diethylaminophenyl)-3-(2- phenylindol-3-yl) phthalide.

References Cited UNITED STATES PATENTS 2,505,486 4/1950 Green. 3,244,5494/ 1966 Farnham et al. 3,268,537 8/1966 Gosnell et al. 3,336,337 8/1967Gosnell. 3,455,721 7/1969 Phillips et a1. 3,491,111 1/1970 Lin.

MURRAY KATZ, Primary Examiner US. Cl. X.R.

